What is a Bypass Instruction?

The Bypass Instruction is an IEEE 1149.1 mandatory instruction which selects the single bit Bypass register between the TDI and TDO. The Bypass Instruction bit pattern shall be all logic 1s in the Instruction Register and must decode to the Bypass instructions. It is also possible to decode other bit patterns into a Bypass Instruction.

Example of a Bypass Instruction with an 8-bit instruction length:
"BYPASS (11111111)," &